1,552 research outputs found
Does beak size affect acoustic frequencies in woodcreepers?
We assessed the effect of beak morphology on the acoustic structure of woodcreeper (subfamily Dendrocolaptinae) songs using a comparative analysis of independent contrasts. For the song of each species, we measured the maximum and minimum frequencies, the bandwidth, and the emphasized frequency. Residuals of variationin beak length and acoustic frequencies after controlling for body size and phylogeny were calculated for each species and compared. We found a negative relationship between the residuals of acoustic frequencies and the residuals of beak length. This relationship was significant for emphasized frequency when we excluded two open-habitat species, Scimitar-billed Woodcreeper (Drymornis bridgesii) and Narrow-billed Woodcreeper (Lepidocolaptes angustirostris).This result is consistent with the hypothesis that the suprasyringeal vocal tract has resonating properties that affect the frequency spectrum of the song.Fil: Palacios, María Gabriela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentin
Edición de genes mediante crispr-cas9: más que Cortar y pegar
En esta revisión se exponen las características y aplicaciones de CRISPR-Cas9, un
sistema inmune adaptativo propio de algunas especies de bacterias y arqueas que lo
utilizan para defenderse de bacteriófagos. Fue descubierto por el doctor español
Francisco Mojica cuando se encontraba investigando sobre un tipo de arquea en las
salinas de Santa Pola (Alicante).
El mecanismo inmune de estos sistemas consta de tres fases donde un ARN guía forma
un complejo proteico con una proteína nucleasa llamada Cas9 para así poder escindir el
ADN del organismo exógeno y evitar su infección. Debido a la simpleza de su
mecanismo, CRISPR-Cas9 lleva siendo utilizado por diversos grupos de investigadores
desde 2013 con el objetivo de convertirse en una nueva herramienta de terapia génica
que permita modificar el genoma de personas que sufran enfermedades con componente
genético. El propósito es introducir los componentes en un vector, viral o no viral, que
sea capaz de alcanzar la célula diana y cortar selectivamente una secuencia del ADN
que posteriormente será reparada por los métodos de recombinación HDR Y NHEJ.
Los sistemas CRISPR-Cas9 presentan numerosas ventajas frente a otros tipos de terapia
génica como ZFN o TALEN como son su bajo coste y su fácil diseño. Sin embargo, la
reparación del gen anómalo y los cambios no deseados en el genoma son aspectos que
los investigadores deberán de solventar para conseguir una herramienta biológica segura
y eficaz.
Por último, se recoge información sobre los últimos avances hasta la fecha y sobre los
ensayos preclínicos basados en este sistema, profundizando en las enfermedades
hereditarias retinianas debido a las características particulares del ojo que lo convierten
en un órgano ideal para ser tratado con sistemas CRISPR-Cas9.Universidad de Sevilla. Doble Grado en Farmacia y Óptica y Optometrí
First principles study of Bi dopen CdTe thin film solar cells: electronic and optical properties
Nowadays, efficiency improvement of solar cells is one of the most important issues in photovoltaic systems and CdTe is one of the most promising thin film photovoltaic materials we can found. CdTe reported efficiencies in solar energy conversion have been as good as that found in polycrystalline Si thin film cell [1], besides CdTe can be easily produced at industrial scale
Impacto del neopentecostalismo en la identidad de los bautistas de Cali, Colombia:Un análisis de la construcción de la identidad bautista en Colombia y sus variaciones en la historia presente 1990-2010
This research has analyzed the process of formation of Baptist identity in Colombia and its variations in the course of its history. In the first part, a review was made of the most notable research on Baptist identity among Baptists in other parts of the world, emphasizing the starting points that these studies have taken. Our emphasize that Baptist identity is a permanent process of construction, renewal and new construction. Some of the authors who have followed this point of view are: Steven Harmon, Curtis Freeman, James McClendon Jr., Paul Fiddes and Bill Leonard. From a more historiographical perspective, the authors who have served us are: Jean Pierre Bastian, José Míguez Bonino and Heinrich Schäfer. In the second part, we describe and analyze some aspects of the history of Baptists in Colombia. In each case we mention significant aspects of the formation of the Colombian Baptist identity, from ethnic, political, religious and generational factors, among others. In the third part, our focus has been the analysis of the construction of the Baptist identity in Colombia with a particular look at the case of the city of Cali, Colombia. We have differentiated between endogenous and exogenous factors in the formation of Baptist identity, describing each one while analyzing their impact and results in the Colombian way of being Baptist. We have mentioned the means used for this identity formation as well as the product itself: the resulting Baptist identity. In the fourth part, we focus on the Baptists of Cali and on the period 1990-2010, because there the Baptists began to experience several changes that at the same time contributed to the formation of a new Baptist identity. We have affirmed that at least three factors were important in the development of a new stage of Baptist identity formation: generational, organizational, and theological. The fifth part describes, exposes, and analyzes the neo-Pentecostal boom and its relationship with the Baptists, since at least two of the most important churches of this current emerged among the Baptists, either because of the origin of their leaders or because of their ecclesial origin, which before the Baptist division had already separated from the denomination. In the sixth part, a more reflective and prospective proposal is presented that Baptist churches should follow to compile the inherited Baptist identity with the constructions that have been elaborated in the Colombian Baptist history and in the churches of Cali. In the conclusions there are a series of observations, since we emphasize that the Baptist identity has not been something static and finished, but that it is constantly being constructed. That in the impact of Neo-Pentecostalism we do not see a single fact but the accumulation of several factors that over time were configured to favor a new construction of Baptist identity. That Neo-Pentecostalism did not affect exclusively Baptists but has been a generalized fact at the transnational and interdenominational level, producing new forms of church organization and promoting new roles of participation in society
Enhancement of optical absorption in Ga-chalcopirite-based intermediate-band materials for high efficiency solar cells
We present absorption properties enhancement for two CuGaS2-based intermediate-band materials, as promising compounds for high efficiency, lower-cost photovoltaic devices. Previous band diagrams calculations predicted that these materials present a partially filled localized band within the band gap of the host semiconductor, which would increase the absorption of low-energy photons, creating additional electron–hole pairs respect to a conventional semiconductor. This could ideally result in an increase of the photocurrent of the cell without the fall of the open-circuit voltage. In this paper we show, using density functional methods, the effect of this intermediate band on the optical properties of the derived alloys. We highlight the significant enhancement of the absorption coefficient observed in the most intense range of the solar emission and we study the reflectance and transmittance properties of the materials in order to understand the effect of the thickness of the sample on the optical properties. We compare two different substituents of the Ga atoms in CuGaS2, namely, Ti and Cr atoms, able to form the intermediate-band material, and their interest for photovoltaic applications
First language acquisition corpora in English and their influence on other languages
Traballo Fin de Grao en Lingua e Literatura Inglesas. Curso 2015-2016This Traballo de Fin de Grao was initially conceived as an exploration on how corpora of language acquisition in English influenced (or not) corpora in other languages, namely in Spanish.
The paper can be seen as having two differentiated parts. The first one provides the background for the topics that we wan to address, which can be grouped in two disciplines of the linguistic studies: Corpus Linguistics and Psycholinguistics (more specifically, first language acquisition). The second part presents an analysis of language acquisition corpora in English. The corpora are firstanalyzed and then confronted with one in Spanish. Chapter 3 functions as a pivot for the two parts. It brings together Corpus Linguistics and first language acquisition in Brian MacWhinney and Catherine Snow’s CHILDES projec
Simulation of the formation of clusters of bioconjugated FeO nanoparticles after their specific interaction with a biomarker
Trabajo Fin de Máster en Física de la Materia Condensada y de los Sistemas Biológicos (especialización en biofísica)In this work, we have built a computational model to perform a comprehensive study of the formation of clusters of nanoparticles functionalized with a ligand which interacts specifically with a biomarker. In our model the interaction between the nanoparticles and the biomarkers is always mediated by the ligands and the only interaction between the nanoparticles is a Lennard-Jonnes force that prevents them from overlapping. The influence of the concentration of nanoparticles and biomarkers and the number of ligands per nanoparticle in the mean size, compactness, and dispersion of sizes of the clusters has been studied using several combinations of parameters. The results have been compared with experimental measures to check the validity of our model and we have found out in which ranges of parameters our model is valid and in which ranges there are non-negligible interactions that
we are not considerin
La dignidad humana en la jurisprudencia constitucional colombiana: un estudio sobre su evolución conceptual
Artículo de investigaciónEl presente estudio hace una reflexión sobre los fundamentos teóricos y filosóficos en los que se ha apoyado la jurisprudencia constitucional Colombiana para atribuirle valor al concepto de Dignidad Humana, dentro de una línea jurisprudencial propuesta. Así mismo, se determinará el grado en que el concepto ha sido modificado a lo largo de la historia de la Honorable Corte, basado en las sentencias hito.PregradoAbogad
Photonic Pulse Shaping Techniques for Arbitrary Waveform Generation
The motivation of this thesis is to explore the generation of arbitrary microwave waveforms through photonic means, showing the advantages they may offer. Some techniques will be presented for this purpose, as well as their applications. Firstly, the technique known as Direct Space To Time Mapping (DST) will be presen-+ted, which as the name properly says, turns the spatial profile into the time profile of the beam. Then, we will present the main technique of the thesis, which shows a great analogywith the DST. This technique is known as Frequency to Time Mapping (FTM) orDirect Fourier Transformation (DFT). In order to derive the expressions needed for the understanding of the DFT, dispersion theory in media will be explained starting from the macroscopic Maxwell equations derived in the appendix. It will be seen how combining spectrum shaping techniques along with the DFT we are able to generate an arbitrary radio-frequency waveform. After being mathematically derived, simulations will be performed to put numbers and further prove of the theory. The achievable time bandwidth product (TBWP) will also be derived and later compared to the one obtained by Matlab simulation. Furthermore, the DFT will then be applied for time reversal by photonic means. A microwave signal up to 10 nanoseconds long can be time-reversed using fibers, as it will be proved in theory and simulation. Applications related to these microwave generation techniques will also be explored, showing the research interest of this cutting-edge discipline
- …